The invention is directed to a spirit level having a bubble tube containing a liquid with an air bubble therein used by tradesman and the like for checking slope angles of drainage pipe or the like and is an advancement over the polyfunctional spirit level covered in U.S. Pat. No. 4,653,193 which I am a co-inventor.
Various attempts have been made in the past to develop carpentry levels and the like that can be used to check alignment surfaces relative to one another and also determine the angle, that certain surfaces are disposed with respect to the horizontal and/or vertical plane.
Some of the prior art devices that have been developed comprise nothing more than elongated rigid tools having a plurality of bubble elements and other angular indicating means associated therewith.
Other prior art devices employ a spirit level that is latterly or vertically translatable along a flat edge support member.
Still other prior art devices employ a spirit body level devices, wherein the levels sections are pivotally secured to one another.
Yet other spirit-level devices include one or more magnets or magnetic tape for attaching the spirit levels to ferro metal objects during use and storage.
Examples of some of the aforementioned prior art devices can be found in the following U.S. Pat. Nos. 2,398,851; 2,419,451; 2,879,606; 3,435,533; 3,820,249; 4,419,833 and 4,607,437.
While all of the above cited references are adequate for their intended purpose, they leave a lot to be desired from the standpoint of being an all around multi-purpose tradesman level. In particular, these devices are generally large in size and therefore are awkward to carry on the person and are not capable of reading a plurality of different slope angles.
U.S. Pat. No. 4,653,193 of which I am a co-inventor teaches a spirit level adapted for use as an declination monitor for two different angles of declination that has found wide acceptance in the building trades. My present invention provides an advancement over that level in that it will read an additional angle of declination and yet smaller in size for easy transport.
Obviously, a level that is small in physical size that can be used to measure a plurality of discrete angles of declination and can be used to approximate those angles of declination falling between certain predetermined discrete slope angles would find immediate success especially in the building trades where a plurality of certain discrete declination angle measurements are required.